Mr Ben. In the II business we have a term for young drones, to young to mate. They are called fuzzies due to all the hair on thorax. Fuzzies are to young and cannot be properly inverted. So if you grab a fuzzie by mistake, no problem they don?t work, they only partially invert. After 10 days, HP say 14, close enough, the drones invert easily.
Beepro made a comment about killing drones, so noted, however when I think how a drone dies naturally, I have no problem with a quick kill inverting method. Head first, then throax and almost all invert properly, unless to young. The invert method is easy, maintaining sterile conditions is not easy.
Blessings